1. Field
The following description relates to an electrode for a super-capacitor, a super-capacitor including the same, and a method of preparing the electrode.
2. Description of the Related Art
Examples of energy storage devices using an electrochemical principle include secondary batteries and electrochemical capacitors. Secondary batteries have high energy density per unit weight or unit volume, but have a short lifetime, a long charging time, and a low power output density. Electrochemical capacitors are super-capacitors that have a specific capacitance at least 1000 times greater than that of a conventional electrostatic capacitor. Also, electrochemical capacitors have a long lifetime, a short charging time, and a high power output density, but have a low energy density.
Electrochemical capacitors can be categorized into electric double layer capacitors, which use an electric double layer principle, and pseudocapacitors, which use a pseudocapacitance generated by an electrochemical Faraday's reaction. Pseudocapacitors have a specific capacitance at least ten times greater than that of electric double layer capacitors.
Electrodes used in pseudocapacitors include metal oxides, which enable charging/discharging at the surface of a metal oxide layer through an oxidation-reduction reaction. The oxidation-reduction reaction occurs only at the surface of a metal oxides layer. Thus, when the surface area of a metal oxide layer is larger, the metal oxide layer stores a larger potential. Thus, an electrode that has such a structure that maximizes the surface area of a metal oxide layer is required.